Wondering when babies can drink water in addition to breast milk or formula?

Little ones generally don’t need water for the first few months — and even when you do add H2O to the mix, your baby will just need a few sips.

Here's what every parent needs to know about when babies can start drinking water.

Can babies drink water?

Babies should only begin drinking sips of water once they start eating solid foods. Before then, babies get the hydration they need from formula and/or breast milk.

When can babies drink water?

So when can you give water to your baby? Most experts suggest that you wait until you’ve started solids, when your little one is around 6 months old. You can start solids between 4 and 6 months old, but experts recommend waiting until your baby is closer to 6 months in most cases.

Once your baby starts drinking water, offer a little at a time from a sippy cup if she'll take it. Babies usually can’t get too much water from a cup (only a bottle) — plus it’s good practice for when all of your baby’s drinks will come from a cup.

If your little one will only drink water from a bottle for the time being, that's okay as long as you monitor (and limit) how much she's getting.

How much water can my baby drink?

From about 6 months on, babies need 4 to 6 ounces of water a day, or just over half a cup of water. Some may like to have more, while others (especially breastfed babies) may not need any extra. But ask your pediatrician how much your little one needs before you offer her water.

Why can’t very young babies drink water?

Infants get all the water they need from breast milk or formula, which keeps them well-hydrated. There are also risks associated with giving a baby water before she's old enough, including:

  • Nutrient deficiencies
  • Weight loss
  • Electrolyte imbalances

Risks of giving your baby water too soon

Very little babies can't drink water because of the following risks:

  • A lack of nutrients. Babies who satisfy their appetite and their need to suck with bottles of water miss out on important nutrients they get from breast milk and formula feedings.
  • Insufficient weight gain. If your baby regularly drinks water in addition to breast milk or formula, she isn’t filling up on food. Over time, that means your baby won’t have the calories she needs to gain the appropriate amount of weight.
  • Decreased milk supply. If you’re breastfeeding, giving your baby water can ultimately decrease your milk supply, since babies who fill up on water will feed less at the breast.
  • Electrolyte imbalances. Letting your baby drink large amounts of water can lead to water intoxication, a potentially dangerous condition where electrolytes (like sodium) in a baby’s bloodstream become diluted. This can impact a baby’s normal body functions, resulting in symptoms like seizures.

Benefits of giving your baby water

Water benefits older babies 6 months and up by helping them stay hydrated, which:

  • Transports nutrients and oxygen to cells while helping remove waste
  • Keeps joints and tissues lubricated
  • Maintains blood volume
  • Eliminates the need for fruit juice (which pediatricians suggest avoiding before the age of 1 anyway — and then only offering it in very limited quantities, if at all)

Should babies drink water when it’s hot outside?

Many doctors recommend that babies drink small sips of water or milk when it’s very hot outside to reduce the risk of dehydration, but be sure to check with your child’s pediatrician first. You can also offer more breast milk or formula.

Signs of dehydration in babies

If you’re concerned that your child isn’t getting enough fluids because she's sick or it’s extremely hot outside, watch out for these signs of dehydration in babies:

  • Fewer than six wet diapers in 24 hours
  • Dark yellow urine
  • Cracked lips
  • Tearless crying (crying with few or no tears)
  • Dry skin that doesn’t bounce back when gently pressed
  • Sunken eyes
  • Listlessness
  • Sunken fontanelle (the "soft spot" on the top of her head)
  • Extreme fussiness
  • Unusual sleepiness
  • Cold hands and feet

When to call the doctor

If your baby is sick with diarrhea and/or is vomiting, call your child’s doctor for tips to ensure your little one stays hydrated. Also call the pediatrician if your child shows any signs of dehydration.

One last tip: Say no to fruit juice until your baby’s at least 1 year old, if at all. Not only does juice fill up your infant’s tiny tummy, leaving less room for milk and food, but the sugar in juice can cause stomach cramping and diarrhea in young babies.

Although friends and relatives might say it’s necessary to offer babies water in the first months of life, it’s best to hold off until your little one starts solids to avoid potential health problems. You’ll be regularly serving the clear stuff before you know it!